列表理解Python和具体项目

Question

我有一个这样的名单：

list_input = [(a,b), (a,c), (a,d), (z,b), (z,e)] 

我想提取b，c和d时启动“一”不与“Z”，并把在列表

我想不出如何去做，有什么建议？

Answer 1

过滤器上的第一个值列表项，收集第二：

[second for first, second in list_input if first == 'a'] 

演示：

>>> list_input = [('a', 'b'), ('a', 'c'), ('a', 'd'), ('z', 'b'), ('z', 'e')] 
>>> [second for first, second in list_input if first == 'a'] 
['b', 'c', 'd'] 

Answer 2

;或

list_input = [("a","b"), ("a","c"), ("a","d"), ("z","b"), ("z","e")] 

print ([x[1] for x in list_input if x[0]=="a"]) 

>>> 
['b', 'c', 'd'] 
>>> 

用索引操纵它。您也可以显示该特定对;

print ([(x,x[1]) for x in list_input if x[0]=="a"]) 

输出;

>>> 
[(('a', 'b'), 'b'), (('a', 'c'), 'c'), (('a', 'd'), 'd')] 
>>> 

Answer 3

你也可以做到这一点明确：

In [8]: [list_input[i][1] for i in xrange(len(list_input)) if list_input[i][0] =='a'] 
Out[8]: ['b', 'c', 'd']